TUBE PICKING MECHANISM WITH UNIVERSAL PICKING HEAD AND CACHE

Abstract

A tube picking mechanism is suitable for use in an automated, ultra-low temperature (e.g., 80 C.) storage and retrieval systems which stores biological or chemical samples. The samples are contained in storage tubes held in SBS footprint storage racks that are loaded into trays located within an ultra-low temperature freezer compartment (80 C.). The tube picking mechanism includes a picking head and a cache that can accommodate sample tubes and vials of different sizes and diameters

Claims

1. An automated, ultra-low temperature sample storage and retrieval system comprising: a freezer body having an ultra-low temperature, insulated compartment that is maintained at an ultra-low temperature from about 50 C. to 90 C. under normal operating conditions when biological or chemical samples are being stored in the ultra-low temperature compartment; at least one freezer rack having trays for storing sample storage containers holding biological or chemical samples, wherein at least some of the sample storage containers are tube racks which hold sealed sample tubes containing biological or chemical samples; a robot located within the ultra-low temperature freezer compartment for transporting storage sample containers within the freezer compartment; an access module for introducing sample storage containers into the ultra-low temperature freezer compartment and for retrieving storage containers from the ultra-low temperature freezer compartment; and a tube picking mechanism located within a tube picking chamber, there being a shuttle door which provides access when open between the tube picking chamber and the ultra-low temperature storage compartment within the freezer, the tube picking mechanism comprising: a shuttle for moving tube storage racks through the shuttle door from the ultra-low temperature freezer compartment into the tube picking chamber and vice versa; a tube picking head having a pair of opposing gripping jaws configured to hold a sample tube by griping a sidewall of the sample tube when the gripping jaws are closed, wherein the distance between the opposing gripping jaws when closed is adjustable depending on the diameter of the sample tube being held; and a cache having two parallel banks of vertical cam plates and two parallel axels, wherein the vertical cam plates in each bank are mounted on a respective axel and able to pivot independently of the other vertical cam plates mounted on the axel from a home position when a sample tube exerts force against an inner edge of the respective vertical cam plate.

2. The system recited in claim 1 wherein the inner edges of the vertical cam plates on one bank of the cache are separated from the inner edges of the vertical cam plates on the other bank by an elongated space.

3. The system recited in claim 2 wherein the inner edges of the respective vertical cam plates have an arcuate cam profile that is oriented with an upper end of the edge being spaced farther away from the opposing bank than a lower end of the edge, and the respective vertical cam plate is mounted on the respective axel so that the plate rotates inward from the home position when a sample tube is moved downward between the respective cam plate and the opposing bank of plates such that a point of contact between the inner edge and the sidewall of the sample tube is tangential.

4. The system recited in claim 2 wherein the distance between the respective parallel axels is adjustable.

5. The system recited in claim 1 wherein each vertical cam plate has a center of mass offset from the respective axel such that the plate rotates towards the home position as the sample tube is withdrawn upward from the cache, and the cache includes a guide member for each bank which stops the rotation of the respective vertical cam plates in the home position.

6. The system recited in claim 1 wherein the tube picking head includes an actuator, a linkage connecting the actuator to the gripping jaws and springs in the linkage connecting the respective gripping jaw to the linkage, wherein the actuator is activated to open and close the gripping jaws and springs in the linkage enable the distance between the opposing gripping jaws when closed to adjust depending on the diameter of the sample tube being held.

7. The system recited in claim 1 wherein the tube picking mechanism further comprises: a presenter push pin that is oriented vertically and can be moved in a horizontal direction and a vertical direction, wherein the presenter push pin is able to be located below the shuttle when it is located within the tube picking chamber and move upward to contact a bottom wall of a sample tube in a tube rack on the shuttle and the presenter push pin is able to be located below the cache a move upward through an elongated slot in a base of the cache to the push a sample tube temporarily upward from the elongated space in the cache between the parallel banks of vertical cam plates.

8. The system as recited in claim 7 wherein the gripping head also includes a vertical shucker rod that moves vertically in alignment with the presenter push pin in order to press downward on the cap of the sample tube while the presenter push pin pushes upward on the bottom of the sample tube in order to hold the sample tube and raise the sample tube from a tube rack in the shuttle or the cache so that the gripping jaws are able to close against the sidewalls of the tube to hold the tube and move the tube, and in order to hold the sample tube to allow the gripping jaws to release and lower the tube in to a receptacle in a tube rack on the shuttle or into the cache.

9. The system recited in claim 1 wherein each gripping jaw includes two levels of v-grooved jaws which are aligned vertically so that a sample tube held in the gripping head is held vertically.

10. The system recited in claim 1 further comprising a y-axis linear drive mechanism located within the tube picking chamber which is mounted to the frame of the tube picking mechanism and moves the shuttle horizontally along a y-axis such that the shuttle resides within the 80 C. freezer compartment when the y-axis linear drive mechanism is fully extended and resides within the tube picking chamber when the y-axis linear drive mechanism is fully retracted.

11. The system recited in claim 8 further comprising a one-dimensional bar code reader for identifying and reading a bar code on a sidewall of a sample tube picked and lifted by the shucking piston and the presenter push pin, and a mirror located in the tube picking chamber such that the picked and lifted sample tube can be located between the one-dimensional bar code reader and the mirror.

12. In an automated, sample storage and retrieval system having trays for tube racks holding biological or chemical samples in sample tubes, a method of retrieving sample tubes from the system comprising the steps of: providing a tube picking mechanism located in a tube picking chamber for picking sample tubes one at a time from one or more source tube racks stored in the system and placing the picked samples tubes in one or more destination racks for retrieval from the system, wherein the tube picking mechanism is capable of picking a sample tube from a tube rack for a variety of sample tubes having a range of diameters; providing a cache that is capable of temporarily storing sample tubes having a range of diameters vertically in the tube picking chamber; shuttling a first source rack into the tube picking chamber, wherein the first source rack contains sample tubes having a first diameter; picking at least one sample tube from the first source rack shuttled into the tube picking chamber; placing the at least one sample tube having a first diameter that was picked from the first source rack with the tube picking mechanism into the cache to temporary hold the sample tube vertically within the tube picking chamber; shuttling the first source rack from the tube picking chamber after the at least one sample tube has been picked from the first source rack and placed in the cache; providing a first destination rack intended to be removed from the system through the access module, wherein the first destination rack is configured to hold sample tubes having the first diameter; shuttling the first destination rack into the tube picking chamber and loading the at least one sample tube having the first diameter with the tube picking mechanism from the cache into the first destination rack; shuttling the first destination rack containing the at least one sample tube having a first diameter from the tube picking chamber; removing the first destination rack from the system through the access module in order to retrieve the at least one sample tube having a first diameter; shuttling a second source rack into the tube picking chamber, wherein the second source rack contains sample tubes having a second diameter, which is different from the first diameter; picking at least one sample tube from the second source rack shuttled into the tube picking chamber; placing the at least one sample tube having a second diameter that was picked from the second source rack with the tube picking mechanism into the cache to temporary hold the sample tube vertically within the tube picking chamber; shuttling the second source rack from the tube picking chamber after the at least one sample tube has been picked from the second source rack and placed in the cache; providing a second destination rack intended to be removed from the system through the access module, wherein the second destination rack is configured to hold sample tubes having the second diameter; shuttling the second destination rack into the tube picking chamber and loading the at least one sample tube having the second diameter with the tube picking mechanism from the cache into the second destination rack; shuttling the second destination rack containing the at least one sample tube having the second diameter from the tube picking chamber; removing the second destination rack from the system through the access module in order to retrieve the at least one sample tube having the second diameter;

13. The method recited in claim 12 wherein the automated, sample storage and retrieval system includes a freezer compartment maintained at an ultra-low temperature between 50 C. and 90 C. and a shuttle door located between the tube picking chamber and the freezer compartment

14. The method recited in claim 12 wherein the first or second destination rack is shuttled into the tube picking chamber to load selected storage tubes from the cache several times prior to removing the respective destination rack from the system through the access module.

15. The method recited in claim 12 wherein the tube picking mechanism includes a gripping jaw, a shucker rod and a presenter push pin, and the steps of picking a sample tube from a rack or the cache requires that the shucker rod engage the top of the respective sample tube and the presenter push pin engage the bottom of the sample tube, and that the respective sample tube be lifted vertically from the rack or cache to provide clearance for the gripping jaw to grip the sidewall of the picked tube, and further that the presenter push pin releases downward to clear the rack or cache prior to transporting the picked sample tube to another location.

16. The method recited in claim 12 wherein the cache comprises: a cache having two parallel banks of vertical cam plates and two parallel axels, wherein the vertical cam plates in each bank are mounted on a respective axel and able to pivot independently of the other vertical cam plates mounted on the axel from a home position when a sample tube exerts force against an inner edge of the respective vertical cam plate.

17. The method recited in claim 16 wherein the inner edges of the respective vertical cam plates have an arcuate cam profile that is oriented with an upper end of the edge being spaced farther away from the opposing bank than a lower end of the edge, and the respective vertical cam plate is mounted on the respective axel so that the plate rotates inward from the home position when a sample tube is moved downward between the respective cam plate and the opposing bank of plates such that a point of contact between the inner edge and the sidewall of the sample tube is tangential.

18. The method recited in claim 15 wherein the tube picking mechanism further includes an actuator, a linkage connecting the actuator to the gripping jaws and springs in the linkage connecting the respective gripping jaw to the linkage, wherein the actuator is activated to open and close the gripping jaws and springs in the linkage enable the distance between the opposing gripping jaws when closed to adjust depending on the diameter of the sample tube being held.

19. The method recited in claim 15 wherein the presenter push pin is oriented vertically and can be moved in a horizontal direction and a vertical direction, wherein the presenter push pin is able to be located below the shuttle when it is located within the tube picking chamber and move upward to contact a bottom wall of a sample tube in a tube rack on the shuttle and the presenter push pin is able to be located below the cache and move upward through an elongated slot in a base of the cache to push a sample tube upward from the elongated space in the cache between the parallel banks of vertical cam plates.

20. A tube picking mechanism comprising: a shuttle for moving tube storage racks; a tube picking head having a pair of opposing gripping jaws configured to hold a sample tube by griping a sidewall of the sample tube when the gripping jaws are closed, wherein the distance between the opposing gripping jaws when closed is adjustable depending on the diameter of the sample tube being held; and a cache having two parallel banks of vertical cam plates and two parallel axels, wherein the vertical cam plates in each bank are mounted on a respective axel and able to pivot independently of the other vertical cam plates mounted on the axel from a home position when a sample tube exerts force against an inner edge of the respective vertical cam plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is a perspective view of an automated, ultra-low temperature storage and retrieval system, including a tube picking mechanism with universal picking head and cache as constructed in accordance with an exemplary embodiment of the invention.

[0022] FIG. 2 is a view of the ultra-low temperature, automated storage and retrieval system shown in FIG. 1, with the door to the tube picking chamber removed.

[0023] FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, illustrating the tube picking mechanism located within the tube picking chamber which is located adjacent the ultra-low temperature freezer compartment.

[0024] FIG. 4 is a perspective view of a tube picking mechanism constructed in accordance with an exemplary embodiment of the invention.

[0025] FIG. 5 is a front perspective view of various components of the tube picking mechanism constructed in accordance with the exemplary embodiment of the invention.

[0026] FIG. 6 is a perspective view of a portion of the exemplary tube piking mechanism, showing the universal picking head and cache, as well as a mirror to facilitate the reading of bar codes on the vertical walls of sample tubes.

[0027] FIG. 7 is an exploded assembly view of the picking head constructed in accordance the exemplary embodiment of the invention.

[0028] FIGS. 8 and 9 are perspective views illustrating the assembled the picking head.

[0029] FIGS. 10A-10C are downward looking views of the picking head showing operation of the gripping jaws to pick a sample tube from a rack or the cache.

[0030] FIG. 11 is an assembly view of an exemplary embodiment of the universal cache.

[0031] FIG. 12 is a perspective view of the exemplary embodiment of the universal cache.

[0032] FIG. 13 is schematic drawing illustrating operation of the universal cache.

[0033] FIGS. 14A-14J are a series of schematic views showing the operational steps of transferring a sample tube in the tube picking mechanism from a tube storage rack to the universal cache.

[0034] FIG. 15 is a top view showing a sample tube held vertically within the universal cache.

DETAILED DESCRIPTION OF THE DRAWINGS

[0035] The figures illustrate various aspects of an exemplary embodiment of the invention. FIGS. 1 and 2, in particular, show an automated storage and retrieval system 10 configured to store sample storage containers such as racks for holding sealed storage tubes at ultra low temperatures (e.g. 80 C.). Overall the system 10 is similar to the system disclosed above incorporated U.S. Pat. No. 7,861,540. A tube picking mechanism 20 constructed in accordance with the present invention is particularly well suited for use with the automated, ultra-low temperature storage and retrieval system 10 shown in FIGS. 1 and 2, although various aspects of the invention can be used in connection with other systems.

[0036] The system 10, which incorporates a tube picking mechanism 20 constructed in accordance with the invention, is designed to store SBS footprint compatible tube storage racks containing tubes or vials. For example, the system 10 will be used to store tube racks containing arrays of 8 mm storage tubes, or tube racks containing arrays of 16 mm vials, or a combination of racks containing these tubes and vials of this size as well as other sizes. The system 10 generally includes an insulated freezer body 12, an internal freezer rack 18 and robot mechanism 14, a custom insulated door 16. The freezer body 12 can take the form of an upright 80 C. freezer body designed for ultra-low temperature storage for pharmaceutical, biotech, and blood bank applications.

[0037] Several components are on the insulated custom door 16 in this exemplary embodiment of the invention. The door 16 includes an access module 22 in which sample storage containers, such as tube racks, are placed in order for transfer into the storage shelves on the freezer rack 18 within the freezer body 12. An electrical control and pneumatic package is also mounted to the insulated door 16 as are servomotors and magnetic couplers for driving the robot 14. Three electric motors 17 on the door 16 for driving the robot 14 within the freezer body 12 are shown in FIG. 3. The insulated door 16 also includes a tube picking chamber 24 in which a tube picking mechanism 20 resides. A decorative cover 26 is placed partially around the wall of the tube picking chamber 24. A viewing window 28 (e.g., several layers of glass) is provided through the front surface of the decorative panel 26 and the tube picking chamber 24 to allow viewing of the tube picking process. A box on the top of the freezer body 12 can house an electronic controller, power distribution electronics, battery and an inlet port from a compressed dry gas source (not shown). The insulated front door 16 is mounted to the freezer body using hinges 28, and a latch 30 as is known in the art, see FIG. 3. The system 10 includes a monitor 32 and user interface electronics. FIGS. 1 and 2 show a shelf 34 for a keyboard.

[0038] Referring now to FIG. 3, the robot 14 located within the freezer compartment 36 can be instructed to bring a tube rack containing sealed storage tubes of biological or chemical samples to a designated location 38 within the freezer compartment 36. The designated location 38 is accessible by both the robot 14 in the freezer compartment 36 and a shuttle 40 for the tube picking mechanism 20. The tube picking chamber 24 includes a doorway 42 that provides access between the tube picking chamber 24 and the freezer compartment 36 and vice versa. A sliding door 44, which is controlled by a pneumatically controlled mechanism, opens and closes to provide access. In FIG. 3, the door 44 is in the closed position. The door 44 needs to be open to shuttle tube racks in and out of the tube picking chamber 24. Within the freezer compartment 36, the system 10 will typically contain shelves for more than several hundred or more tube racks. When the system 10 is programmed to retrieve tubes from the various source racks, the source racks are fed to the designated location 38 by the robot 14 one at a time. The shuttle tray 40 for the tube picking mechanism 20 receives the chosen source rack at the designated location 38 and transports the source rack into the tube picking chamber 24, at which time the tube picking mechanism 20 picks the selected tubes from the source rack. As described in more detail below, the picked storage tubes are temporarily stored in a universal cache 46, FIG. 4, located within the tube picking chamber 24. When all the tubes have been picked from the chosen source rack, the shuttle tray 40 returns the source rack to the designated location 38 in the freezer compartment 36, and the robot 14 then returns the source rack to its home location in freezer rack 18 in the freezer compartment 36. The robot 14 then retrieves the next chosen source rack and transports it to the designated location 38. This source rack is then shuttled into the tube picking chamber 24 for tube picking as described above. The process is repeated until all the storage tubes of interest have been picked from the respective source racks by the tube picking mechanism 20, or the universal cache 46 becomes full. At that point, a destination rack, which is preferably an empty tube rack, is placed on the shuttle tray 40 by the robot 14 at the designated location 38 in the freezer compartment 36. The destination rack is then shuttled into the tube picking chamber 24 by the tube picking mechanism 20 and storage tubes are loaded from the cache 46 into the destination rack. If it is desired to extract more tubes from the system 10 or it is desired to extract tubes having different sizes and/or diameters, one or more additional source racks and the destination rack are shuttled into the tube picking chamber 24 as necessary. When the destination rack is full, or all of the selected tubes have been loaded into the destination rack, the destination rack is shuttled to the designated location 38 in the freezer compartment 36. From there, the robot 14 transports the destination rack to the access module 22 for extraction from the system.

[0039] FIGS. 4 through 6 show the internal components of a tube picking mechanism 20 constructed in accordance with the exemplary embodiment of the invention. The tube picking mechanism 20 includes a shuttle tray 40 which moves linearly along a y-axis. The door 44 must be opened in order for the shuttle 40 to move into the freezer compartment 36. The door 44 is closed in FIG. 4, and the shuttle 40 is located within the tube picking chamber 24 which is its location during a tube picking operation.

[0040] The tube picking mechanism 20 also includes a tube picking head 48 and a universal cache 46. The specific components of the tube picking head 48 are described in detail with respect to FIGS. 7-9. The tube picking head 48 is mounted to a carriage 50 and in accordance with the exemplary embodiment of the invention is configured to pick sample tubes having a variety of sizes and diameters, for example, sizes ranging from 8 mm tubes to 16 mm vials. The carriage 50 is mounted to a z-axis plate 52. The z-axis plate 52 is in turn mounted to an x-axis plate 54, such that the z-axis plate 52 is movable in an x-axis direction perpendicular to the y-axis. The carriage 50 is attached to the z-axis plate 52 with a z-axis bearing 56, see FIG. 6, that is guided for vertical movement along z-axis rail 58 on the z-axis plate 52. The carriage 50 is clamped to a belt which is driven via a stepper motor in order to move the carriage 50 and the picking head 48 vertically along the z-axis. An optical sensor can be used to sense when the z-axis bearing 56 is in the home position. The z-axis plate 52 is connected to the x-axis plate 54 with an x-axis bearing 60 for guided movement along an x-axis rail 62 on the x-axis plate 54. The z-axis plate 52 is clamped to a belt which is driven via a stepper motor in order to move the z-axis plate 52, the carriage 50 and the picking head 48 horizontally along the x-axis.

[0041] The universal cache 46 is located, in accordance with the exemplary embodiment of the invention, within the tube picking chamber 24. The purpose of the cache 46 is to temporarily store picked tubes within the tube picking chamber 24 until an appropriate time for loading the picked tubes into a destination rack for extraction from the system. The universal cache 46 is configured in the exemplary embodiment of the invention to hold tubes and vials having a variety of sizes, for example, sizes ranging from 8 mm tubes to 16 mm vials. The cache 46 is aligned linearly along the x-axis underneath the picking head 48. The x-axis underneath the picking head 48 is located at a fixed distance along the y-axis which the rack shuttle 40 moves along. Generally, to pick a tube, the shuttle 40 is indexed along the y-axis within the tube picking chamber 24 in order to align a row of tubes in the storage rack on the shuttle 40 in the appropriate y-axis position for the picking head 48. The z-axis plate 52, carriage 50 and picking head 48 are moved along the x-axis to hover over a selected storage tube in the rack on the shuttle 40. The picking head 48 then picks the selected tube from the rack on the shuttle 40. Once the selected tube is picked from the rack, the z-axis plate 52, carriage 50 and picking head 48 are moved along the x-axis to a selected position over the universal cache 46, and the picked tube is set into the cache 46.

[0042] A sidewall 64 of the picking chamber 24 includes a one dimensional barcode reader 68, such as a DC-powered reader from Keyence. The one dimensional bar code reader 68 is mounted to the wall 64 so that its field of view extends into the tube picking chamber 24 in line with the tube picking head 48 and a mirror assembly 66. The mirror assembly 66 is provided on the carriage 50 for the picking head 48 on the side opposite the barcode code reader. As shown in FIG. 6, the mirror assembly 66 includes two mirrors, e.g., intersecting at an approximate 120 degree angle along the centerline of the picking head 48. When a sample tube is held in the picking head 48, the bar code reader 68 is able to view the side of the sample tube facing the bar code reader, and is also able to view each of the angled mirrors. With this configuration, the bar code reader 68 is able to read a bar code applied to the sidewall of a sample tube held in the picking head 48, whether the bar code is facing the bar code reader or one of the mirrors in the mirror assembly 66.

[0043] The z-axis plate 52 includes not only a vertical drive for the carriage 50 and picking head 48, but also a vertical drive for a presenter push pin assembly 70. The presenter push pin assembly 70 includes a vertical presenter push pin 72 that moves with the z-axis plate 52 such that it remains aligned along the z-axis of the picking head 48, and is configured to move up and down along the z-axis below the shuttle 40 and the universal cache 46. The presenter push pin 72 is mounted via a mounting bracket attached to the end of an L-shaped presenter arm 74. The presenter arm 74 has a vertical rail 78 that is mounted via linear bearings 76 on the z-axis plate 52. A stepper motor mounted to the z-axis plate 52 drives a pulley and belt, and the presenter arm 74 is clamped to the belt such that operation of the stepper motor causes the presenter push pin 72 to move upward or downward along the z-axis for the picking head 48. Note that the motion of the presenter arm 74 and pin 72 along the z-axis can be independent of the z-axis motion for the picking head 48.

[0044] Referring to FIG. 5 in particular, the picking head 48 includes a shucker rod 81 (shown in phantom) which moves vertically up and down to facilitate picking of tubes and vials by the picking head 48 and to facilitate removal of a picked tubes and vials from the picking head 48. The operation of the shucker rod 81 is controlled, preferably, with a high resolution linear motor. The shucker rod 81 can be positioned intermediately between a fully retracted position and a fully extended position.

[0045] FIGS. 7-9 show the construction of the tube gripping mechanism 80 of the picking head 48. The tube gripping mechanism 80 includes two gripping jaws 90, 92 that are configured to grip the sidewall of a sample tube or vial being picked. Each gripping jaw 90, 92 has an upper V-shaped gripping pad 118, 122 and a lower V-shaped gripping pad 120, 124. The respective upper V-shaped gripping pad 118, 122 and lower V-shaped gripping pad 120, 124 are configured to hold the tube or vial vertically when held by the tube gripping mechanism 80. The upper gripping pads 118, 122 are chamfered to help guide the shucker rod 81 between the gripping jaws 90, 92 when it is moved downward through the gripping mechanism 80. The lower gripping pads 120, 124 are chamfered to help guide the presenter pin 72 between the gripping jaws 90, 92 when it is moved upward through the gripping mechanism 80. A pneumatic actuator 116 is activated to open and close the gripping jaws 90, 92 via a spring-loaded linkage mechanism. A u-bracket 114 is driven be the actuator 114 between an open position and a closed position. Linkage arms 94, 96, 98, 100, linkage rods 102, 104, 106, 108 and springs 110, 112 form the spring-loaded mechanism which moves the gripping jaws 90, 92 between the open position and the closed position. The springs 110, 112 stretch when the gripping jaws 90, 92 are closed around a sample tube thereby enabling the tube gripping mechanism 80 to hold tubes and vials having a variety of diameters.

[0046] The tube gripping mechanism 80 has an upper plate 82 and a lower plate 84, which house the components of the spring loaded linkage mechanism. The upper plate 82 has a central opening 86, and the lower plate 84 also has a central opening 88, which is aligned with the central opening 86 on the upper plate 82 when the mechanism 80 is assembled. The plates 82, 84 include slotted openings 126A, 126B, 126C, 126D and 128A, 128B, 128C, 128D for guiding the motion of linkage rods 102, 104, 106 and 108, which in turn moves the ends of the linkage arms 94, 96, 98 and 100 to position the gripping jaws 90, 92 in response to the activation of the pneumatic actuator 116 and the shifting of the u-bracket 114. Referring to FIGS. 10A through 10C, FIG. 10A shows an empty tube gripping mechanism 80 in a fully closed position, FIG. 10B shows the tube gripping mechanism in a fully open position preparing to hold a sample tube 134, and FIG. 10C shows the tube gripping mechanism in a closed position with a sample tube 134 held by the gripping jaws 90, 92. In FIG. 10A, the u-bracket 114 is in a retracted or closed position, such that the linkage rods 104, 106 are positioned at the outer end of the respective slots 126C and 126D. The springs 110, 112 are connected between linkage arms 96, 98 and 94, 100 respectively, and pull the linkage arms as well as linkage rods 102, 108 and gripping jaws 90, 92 together to the fully closed position.

[0047] Each side of the u-bracket 114 includes a triangular opening 130A, 130B, each having an angular cam surface 130A, 130B. When the actuator 116 is activated to extend the u-bracket 114 as shown in FIG. 10B, the respective angular cam surface 130A, 130B moves the linkage rods 104, 106 inward within the respective slot 126C, 126D, which in turn pushes the ends of the linkage arms connected to the rods 104, 106 inward. This has the effect of pushing the rods 102, 108 in slots 128C, 128D and the gripping jaws 90, 92 outward against the force of the springs. At this point, a sample tube 134 can be placed between the gripping jaws 90, 92 as shown in FIG. 10B. Then, as shown in FIG. 10C, the actuator 116 is activated to retract the u-bracket 114, which in turn allows the springs 110, 112 to pull the gripping jaws 90, 92 together against the sidewall of the sample tube 134. Because the sample tube 134 is between the gripping jaws 90, 92, the rods 104, 106 do not slide to the outer ends of their respective slots 104, 106, see FIG. 10C. Accordingly, the tube gripping mechanism 80 is capable of holding tubes and vials having a wide variety of diameters.

[0048] The components of a universal cache 46, constructed in accordance with the exemplary embodiment of the invention, are shown unassembled in FIG. 11 and assembled in FIG. 12. The cache 46 has two parallel banks 136A, 136B of vertical cam plates 138 mounted on two parallel axels 140A, 140B. The axels 140A, 140B are mounted through mounting holes 144 in sidewalls 146A, 146B of the cache base 142. Set screws 145 hold the axels 140A, 140B in place on the cache base 142. A longitudinal slot 148 is located through the floor of the base 142 between the banks 136A, 136B of vertical cam plates 138. The vertical cam plates 138 in each bank 136A, 136B are mounted on the respective axel 140A, 140B and are free to pivot independently of the other vertical cam plates 138 mounted on the axel. The cam plates 138 sit naturally in a home position as shown in FIG. 12. A longitudinal homing plate 150A, 150B is located on each side of the cache base 142, and serves to stop the rotation of the cam plates 138 in the respective home position when the cache 46 is empty. In the exemplary embodiment, the length of the parallel banks 136A, 136B of vertical cam plates 136 is sufficient to hold 12 tubes or vials spaced at 9 mm center to center spacing, e.g., a total length of 142 mm. A small distance can be provided between the end wall of the base and the cam plate 138 adjacent the end wall as shown by reference number 147 in FIG. 12. As long as some cam plates 138 remain beyond the center line of the tube or vial when the space 147 is used, the tube or vial will remain vertical in the cache 46.

[0049] Each vertical cam plate 138 has a center of mass offset from the respective axel 140A, 140B such that the plate rotates towards the home position unless a sample tube is placed in the cache 46 between the banks 136A, 136B. In the embodiment shown, there are three holes in each vertical cam plate 138, namely hole 152 which is used to mount the cam plate on the respective axel 140A, 140B and holes 154 which are included to lighten the respective side of the cam 138 and shift the center of mass so that it naturally rotates to the home position. The longitudinal homing plates 150A, 150B for each bank 136A, 136B stops the rotation of the respective vertical cam plates in the home position.

[0050] Referring to FIGS. 13 and 15, the inner edges 156 of the vertical cam plates 138 on one bank 136A of the cache 46 are separated from the inner edges 156 of the vertical cam plates 138 on the other bank 136B by an elongated space 158. The inner edges 156 of the respective vertical cam plates 138 have an arcuate cam profile that is oriented with an upper end of the edge 156 being spaced farther away from the opposing bank than a lower end of the edge. In the embodiment shown in the drawings, the arcuate edge 156 has constant 40 mm radius. When a sample tube 134 is placed downward into the cache 46, the respective cam plates 138 rotate from the home position as the sample tube exerts force against an inner edge 156 of the respective vertical cam plate 138. The vertical cam plates 138 are mounted on the respective axel 140A, 140B and rotate inward from the home position when a sample tube 134 is inserted such that the point of contact between the respective inner edge 156 and the sidewall of the sample tube 134 is tangential. The weight of the respective cam plates 138 causes the inserted sample tube to self-center between the banks 136A, 136B of cam plates. It is also noted that the cam plates 138 positioned at a location corresponding to the full diameter of the inserted sample tube 134 rotate farther away from the home position than the cam plates located at a position corresponding to an edge of the inserted sample tube 134. The cache 46 also reliably maintains the inserted sample tube oriented in a vertical direction. The thickness of the cam plates 138 should be selected to provide an appropriate resolution for holding tubes and vials having the diameters expected, while at the same time providing sufficient weight so that the cam plates rotate independently. In the shown embodiment, the cam plates are made of steel having a thickness of about 0.060 of an inch. This thickness is suitable to provide an appropriate resolution for holding tubes and vials having diameters ranging from 8 mm to 18 mm, while at the same time providing sufficient weight to overcome ancillary frictional forces that might otherwise impede the independent rotation of the cam plates on the respective axels. Spacers can be placed between the adjacent cam plates and/or the sidewalls of the base in order to prevent sticking if necessary.

[0051] It can be seen that cache 46 is capable of accepting and holding tubes and vials having a variety of diameters. For small tubes having a diameter of 8 mm it is desirable that the distance 158 between the arcuate inner edges 156 of opposing cam plates 138 be approximately 5 mm. This ensures that a sufficient number of cam plates 138 are displaced and rotate when the tubes are inserted. It is possible to adjust the distance 158 in the embodiment of the cache 46 shown in the drawings, e.g. in case the range of diameters of the tubes or vials expected to be stored in the cache 46 needs to be accommodated. The distance 158 is adjusted by changing the height of the respective homing plates 150A, 150B on the cache base 142, which in turn changes the rotational orientation of the cam plates 138 when they are in the home position, but also changes the distance 158. In practice, the adjustment can be done by providing a fixture with a calibrated rib through the slot 148 and between the inner edges 156 of the cam plates 138. Then, the height of the longitudinal homing plates 150A, 150B is set to the appropriate height to support the cam plates 138 defined by the calibrated rib.

[0052] FIGS. 14A-14J are a series of schematic views showing the operational steps of transferring a sample tube 134 from a tube storage rack 160 in the shuttle tray 40 to the universal cache 46. In FIG. 14A, the picking head 48 and the presenter push pin 72 are aligned over a sample tube 134 in a storage rack 160 located on the shuttle tray 40 in the tube picking chamber. The shucker rod 81 is in a retracted position, and so is the presenter push pin 72. FIG. 14B shows the shucker rod 80 in an extended position against the top surface of the sample tube 134. The position of the shucker rod 81 relative to the picking head 80 is controlled using a high resolution linear motor. The control system is programmed with the height dimensions of the sample tube 134 and controls the height of the picking head 48 as well as the linear motor to control the height of the shucker rod 81. FIG. 14C shows the presenter push pin 72 after it has been raised against the bottom of the sample tube 134, and then with downward pressure on the top of the sample tube 134 (cap) from rod 81 and upward pressure on the bottom of the sample tube 134 from the pin 72, raised to lift the tube 134 from the tube storage rack 160. In step 14C, the rod 80 is retracted with the rod 80 and the pin 72 maintaining positive pressure on the top and bottom of the sample tube 34, respectively. This movement places the sample tube between the gripping jaws 90, 92 of the tube gripping mechanism 80, see FIG. 10B. FIG. 14D shows the gripping jaws 90, 92 closing around the sample tube 134, see FIG. 10C. FIG. 14E shows the pin 72 after it is retracted downward. The tube gripping mechanism 80 remains at a height sufficient to ensure that the sample tube 134 clears the rack and other tubes in the rack 160 completely before transporting the sample tube to the cache 46. In FIG. 14F, the picking head 48 and the presenter push pin 72 have been repositioned over the cache 46 with the sample tube 134. The presenter push pin 72 is in a retracted position, and the picking head 48 continues to be in a fully lifted position. FIG. 14G shows the picking head 48 being lowered so that the sample tube 34 hovers over the cache 46, and in particular at a selected location over the space between the banks of cam plates in the cache. The presenter push pin 72 is raised through the slot in the base of the cache and between the banks of cam plates until it engages the bottom of the sample tube 134. FIG. 14H shows the gripping jaws 90, 92 releasing the sample tube 134 while the rod 81 maintains pressure on the top of the tube 134 and the pin 72 maintains pressure on the bottom of the tube 134. FIG. 14I shows the rod 81 being extended to move the sample tube 134 downward into the cache 46, causing the relevant cam plates to rotate. After the sample tube is in place in the cache 46, the pin 72 is retracted and the rod 81 is lifted, see FIG. 14J. The height of the tubes 134 in the cache 46 is stored in the controller. This process is repeated to transfer subsequent sample tubes from source racks on the shuttle to the cache. When all of the desired sample tubes have been placed in the cache, a destination rack is placed on the shuttle tray and the sample tubes in the cache 46 are transported to the destination rack, using a similar process as described in FIGS. 14A-14J to transport the tubes or vials.

[0053] The exemplary embodiment of the invention has been described herein with respect to use with an ultra-low temperature (80 C.), automatic storage and retrieval system. However, many of the features described herein may be useful in storage systems that store samples at freezing temperatures above or below the ultra-low temperature range. Those skilled in the art should appreciate that these features, among others, while useful in connection with tube picking mechanisms located in a tube picking chamber adjacent an ultra-low temperature (80 C.) freezer compartment, are also useful in other applications as well. For example, the tube picking mechanism can be used in applications outside of or not including a cold chamber.